My computer is desktop
Please note that as soon as you connect a PCIe card on the system, the onboard graphics will be disabled automatically. The reason why you are getting this error message is that you have the discrete card connected to the system or the driver you are trying to install is not the correct one.
You can try installing this driver:
In the case you are still having problems to install the driver, I recommend you disconnecting the video card and try installing the driver again.